The present invention refers to a belt for a caterpillar type conveyor, in particular for conveying moulded plastic parts leaving a moulding unit.
As is known, conveyors are used to convey various types of articles, items and parts. The conveyor has an endless belt or band, supported by guides and rollers arranged on a supporting frame. At least one of said rollers is motorised so as to allow the movement of the conveyor belt.
The conveyor belt has in its outward facing surface a plurality of tongues disposed transversally with respect to the direction of travel and protruding outward at right angles to the plane of the conveyor belt. Said transverse tongues serve to generate an abutment surface, so as to prevent the parts from slipping on the conveyor belt, especially if the belt is disposed on an inclined plane.
Various types of conveyor belt are commercially available. One type of conveyor belt has a plurality of tracks shaped as transverse plates disposed side by side and hinged to each other by means of pivot rods, so as to form a substantially flat surface. Said plates are alternated with plates provided with a respective tongue which protrudes outwards at right angles with respect to the plane of the belt.
The plates of the belt are made by injection moulding of plastic material. As a result each plate provided with a tongue is made of hard plastic in a single piece.
Conveyor belts are also known wherein the tongues are made separately from the plates and then fixed to the plates by means of screw means. Clearly in this case also the tongues are made of hard plastic because they must have threaded holes for engagement of the screw means.
In order to adjust the width of the conveyor belt, instead of a single transverse plate a plurality of plate elements brought together alongside each other so as to obtain the desired length can be provided. In this case also the plate elements with tongues are made in a single piece by moulding of plastic material.
The plate members are kept in position thanks to the fact that they are hinged to the respective hinge rods. However, said system does not offer a safe hold of the elements, which are not constrained to each other, but simply placed side by side.
This type of conveyor belt presents drawbacks when it is used to convey moulded plastic items. In fact, when the moulded item leaves the mould it is still warm and the plastic is in a semi-solid state, so it can be easily deformed. If the moulded item falls directly onto the rigid transverse tongues of the conveyor belt, it undergoes a certain deformation because of its weight and the force of gravity due to its fall.
This deformation of the moulded item is unacceptable, especially in the case of items destined to have an aesthetic or design function, such as, for example, parts of vehicles and the like which are on view. As a result, when the deformed item reaches quality control it is rejected, with a consequent economic and production loss.
This drawback is overcome, at least in part, by the conveyor belts of the prior art which have a core of synthetic woven material which is coated with a layer of rubber, wherein transverse tongues to convey the items and undulated side edges to prevent the deadhead from leaving the moulded items are formed.
In this case, when the moulded item falls onto a transverse tongue of soft rubber of the belt, it causes bending thereof and thus the item does not undergo deformation. However, such a type of conveyor belt is extremely expensive. Furthermore, damage to a single tongue or portion of the rubber coating requires replacement of the entire belt, with the result of a considerable economic loss.
U.S. Pat. No. 4,832,138 discloses a conveyor belt according to the preamble of claim 1.
The object of the present invention is to overcome the drawbacks of the prior art, providing a conveyor belt that is suitable for work with moulded plastic articles leaving a mould in the semi-solid state.
Another object of the present invention is to provide such a conveyor belt that is cheap and easy to make.
Yet another object of the present invention is to provide a conveyor belt that is extremely reliable and involves low maintenance and repair costs.
These objects are achieved in accordance with the invention with the characteristics listed in appended independent claim 1.
Advantageous embodiments of the invention are apparent from the dependent claims.
The conveyor belt according to the invention comprises a plurality of transverse plates or tracks disposed side by side and constrained to each other hingedly to form an endless belt, wherein some of said transverse plates have transverse tongues made of soft, rubber-based material which protrude substantially at right angles with respect to the plane of said transverse plates.
The conveyor provided with the belt according to the invention is particularly suitable to be disposed at the output of a moulding or blow-moulding unit. In this manner the moulded items, still warm and in a semi-solid state, on falling onto the transverse tongues cause bending thereof and, therefore, do not suffer any damage.
Further characteristics of the invention will be made clearer by the detailed description that follows, referring to a purely exemplary and therefore non-limiting embodiment thereof, illustrated in the appended drawings, wherein:
FIG. 1 is a perspective exploded view illustrating three elements forming part of a plate or track of the conveyor belt according to the invention, wherein the three elements are seen from above;
FIG. 2 is a perspective exploded view of the three elements of FIG. 1, seen from below;
FIG. 3 is a perspective view of the three elements of FIG. 1 assembled, wherein a portion of transverse tongue has been inserted, and another portion of transverse tongue is illustrated exploded;
FIG. 4 is an enlarged view of a detail of FIG. 3;
FIG. 5 is an exploded perspective view illustrating a transverse bar provided with a transverse tongue of the conveyor belt according to the invention;
FIG. 6 is a top plan view diagrammatically and partially illustrating a conveyor belt according to the invention.